Thread-controlling mechanism for sewing machines



J. R. MOFFATT THREAD CONTROLLING MECHANISM FOR SEWING MACHINES Filed June 22, 1926 4 Sheets-Sheet 1 J. R. MOFFATT THREAD CONTROLLING MECHANISM FOR SEWING- MACHINES Oct. 30, 1928.

4 SheetsSheet 2 Filed June 22, 1926 Oct. 30, 1928. 1,689,957

J. R. 'MOFFATT THREAD CONTROLLING MECHANISM FOR SEWING MACHINES Filed Jun 22, 1926 4 Sheets-Sheet 3 Qg llllllll' 41] "ill Oct. 30, 1928. 1,689,957

7 J. R. MOFFATT THREAD CONTROLLING MECHANISM FOR SEWING MACHINES iled June 22, 1926 4 Sheets-Sheet 4 Patented Oct. 30, 1928. v

ATENT OFFICE.

JAMES R. MOIFA'IT, OI CHICAGO, ILLINOIS, ASSIGNOR TO UNION SPECIAL MACHIN COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS. t

THREAD-CONTROLLING MECHANISM FOB/SEWING MACHINES.

Application filed .Tune 22, 1926. Serial No. 117,724.

The invention relates to new and useful improvements in a thread controlling mechanism for sewing machines, and more particularly to the thread controlling mechanism for up and given up by movable thread eyes mounted on thelooper carrierand cooperat- 7 ing with a stationary member having cam faces and shoulders for properly taking'up and giving up thread.

A further object of the invention is to provide a thread controllingmechanism of the above type wherein the needleguard. is used for controlling the time of release of the thread by the stationary member.

A still further obj ect of the invention is to provide a combined pull-ofl and clamp for the looper thread which is timed so that the looper thread is clamped between the pull-off and the looper whenthe looper is on the forward part of its movement so as to insure the propercontrol of the looper thread by the looper thread controlling mechanism, and wherein said thread clamp releases the looper thread while the looperis on the forward. part of its stroke so that the thread pulled from the supply may be taken up by. the loopor thread controlling mechanism and the looper.

These'and other objects will in partibe' obvious and will in part be hereinafter more fully disclosed.

In the drawings which show by wayof one embodiment of the inventionea a illustration Fignre 1 is a view partly in front elevation and partly infsection, showing more or. less diagrammatically a portion of a sewing machine embodying myfimprovements;

Fig.2 is a side viewof the end of the work supporting armand with thev end cap re-' moved to show the looper and thread control ling mechanism associated therewith Fig. 3 is an enlarged end view ofthe work supporting armwith the end cap removed to show the looper and the thread controlling mechanism, andalso the needles;

looper thread, and

Fig. 4 is a view similar to Fig. 3, but showing the needles all the way-up and the looper at the forward end of its stroke, f Fig. 4 is a side view of the parts shown in Fig. 4, the needles being omitted;

Fig. 5 is a View similar to F ig. 3, but showing a portion only of the end of thework support, and showing the needles all the way down and the looper at the rear end of its of the parts as shown ing the looper retracted sufficiently so that I the thread controlling member on the needle guard is brought closeup to thestationary thread controlling cam;

Fig. 9 is a detail in perspective showing the thread'fingers, thread eyes, the thread clamp constituting Iathread pull-off mechanism and thread clamping device;

Fig. 10 is a view from the end of the machine showing the stationary thread cam, the thread guides, thelooper carrier, the needle guard and the member carried therebywhich cooperates with the stationary thread controlling cam with the looperthread retainedon the upper shoulderof' the controlling cam: Fig. 11is a view from the end ofthe ma" chine showing the looper, the thread guides and the stationary thread controlling cam with the looper thread carried into engage-- ment with the under surface ofthe eccentric portion of the thread'controlling cam N Fig. 12 is a plan view of a portion of the overhanging arm, the needle lever, and the device for clamping and pulling oftv the Fig. 13 is a. sectional view through the overhanging arm and the needle lever, showing the thread clamping and pull-off devicein elevation. y .1

The invention isdirected broadlytoa looper thread controlling mechanism, and consists in the arrangement oft-he movableparts of the thread controlling mechanism very close to the looper so that the control oi the looper thread is very close to the. stitching point llo This enables threads to be used which are very loosely twisted, and liable to stretch or t ar apart. and yet perfect: stitching; made. In carrying out the invention a stationary thread cam is used which is located alongside of the looper and attached to the end of the work supporting arm. Associated with this stationary cam, are thread eyes which are mounted on the looper carrier. These eyes are so disposed on the carrier. and the stationary thread cam is so disposed relative to the carrier. that one eye is on one side of the stationary thread cam. while the other is on the other side of the stationary thread cam. Therefore. the thread running between the thread eyes will be caused to engage the sta' tionary thread cant and moved along" the same. The thread from the supply is led through a guiding tube. which is arranged on the work supporting arm so that the point of delivery of the thread to these movable thread eyes associated with the looper. is midway between the rear end of the stroke. of the thread eyes and the fort ard end of the stroke of the thread eyes. The stationary thread cam is provided with a shoulder, so that the thread passing between the thread eyes engages said shoulder as thelooper moves forward to enter the needle thread loop. At this time, the thread eyes are approaching the thread supply tube, but the engatrement of the thread with theshoulder on the stationary controlling cam, takes up all the slack in the looper thread and pulls the slack in the looper thread back through the eye of the looper as the looper moves forward. This prevents any possible kinking or buckling ot the looper thread between the eye thereof and the material which is liable to push the thread loop to one side and cause the skippine or malformation of stitches. This stationary thread cam has a clearance space into which the thread passes after it leaves the shoulder thereon. Said stationary thread controlling am has an eccentric curved surface against which the thread is carried by the thread eyes as the looper approaches the forward end of its stroke. and this is for the purpose of drawing -fromthe pull-off the thread which is drawn ofi' from the supply on the first part of the forward movement of the looper. The pull-oil has means associated therewith for clamping the thread between the active linger for pulling thethread from the supply and the looper; and this clamping means is active during: the first part of the Forward movement of the looper. but the clamp is released during the latter part of the stroke of the looper and at the time when the thread is carried against this eccentric surface of the stationary thread controlling cam. This sta tionary thread controlling cam has another shoulder which is so associated with the movable thread eyes, that the looper thread extending between the thread eyes will be assess? snapped in front of the shoulder as the looper reaches the forward end of its stroke. As the looper starts on its backward movement. the thread is carried against this forward shoulder and slack in the looper thread taken up so that the looper thread properly positioned for the needle to enter the thread triangle forming the looper thread loop. The controlling member on the needle guard becomes active at this time to prevent the thread from slipping from said torward shoulder until the needle is well down into the thread triangle, a tter which the looper thread is permitted to become disengaged from the t'orward thread shoulder.

Referring more in detail to the drawings, my improved thread controlling mechanism is shown as applied to a sewing machine having an overhanging arm 1 carried by a suit: able standard Mounted in the overhanging arm 1 is a needle bar 2:3, carrying. as shown in the present embodiment ol the invention. three needles. indicated at it. ('ooperatirm with the three needles is a looper 5. This looper 5 is adapted to cooperate with all three needles. entering first the needle thread loop of the lett-hand needle as viewed in Fig. 3, then the middle needle. and tinally the righthand needle. and the needles are set. at ditlerent heights in order to insure the proper timing of the looper and the needles so that the looper will enter all three needle thread loops. The looper is mounted in a looper carrier ti. and the looper carrier (3 is rigidly secured to a looper shaft 7. The looper shaft 7 is mounted in a work supportin; arm 8. and extends lengthwise tln-reol. F uitable means is provided for oscillating the looper sha it T so as to move the looper into and out of the needle thread loops. and also for morinr. the looper shalt endwisc for giving a needle avoiding movement to the looper. The material being stitched is fed oil from the end of the work supporting arm. and therefore. the looper moves back and forth in a plane at right angles to the line (it l'eed. The needle bar is reciprocatcd by means o I a needle. lever 9 of the usual construction.

Mounted on the looper is a neede guard l l. Th s needle guard, so far as its relation to the looper is concerned.- and as to its function as a needle guard. is of the well-known construction. Said needle guard is provided. however. with a projecting: member ll which functions in connection with the thread controllingmechanism as will be hereinafter more tally disclosed. The looper thread is led from the supply through suitable tensdons and thence to a thread slot 12 in an arm 13 seoured to the needle lever 9 by means of a screw 14 pass ng through a slot 1:: in the arm i i. The thread after passing tlnouirh this slot 12. is then led throue'h a thread eve it; in an aria 17 carried by a bracket iii. The bracket id is secured by a screw 19 to the overhanging Hit) lltl

nesaesv of the arm 21, thence through a slot 22 in a bar 23 attached to the bracket 18. Mounted on the arm 13 is a clamping finger 24, which slides beneath the bar 23 and engages and clamps the looper thread which passes through the slot--22. The looper thread after leaving the thread clamp passes through a thread guide 25, and thence to a thread guid ing tube 26. This thread guiding tube 26 eX- tends along the frame to the work supporting arm 8, and along the work supporting arm 8 to the end thereof. The thread passes from the thread guiding tube 26 to a thread guide 27 mounted on the looper ca-rrier6, and thence to a thread guide 28 also mounted on the looper carrier 6. After leaving the thread guide 28, saidlooper thread passes to the eye 29 at the heel of the looper and then to the eye 30 at the point of the looper. These thread guides 27 and 28oseillate with the looper as they are mounted on the looper carrier. They are spaced from each other as clearly shown in the drawings, and between the thread guides is a stationary thread controlling cam 31. This stationary thread controlling cam 31 is secured by means of a screw 32 to a lug 33 attached to the work supporting arm 8 of the machine. The stationary thread controlling cam is provided with a shoulder 34.- which will be referred to hereinafter as the rear shoulder of the stationary thread controlling cam. It is also provided with a shoulder 35 which will be referred to as the forward shoulder of the stationary thread controlling cam. Between these shoulders 34 and 35, the stationary cam is cut away to form a clearance space. The under face 36 of the stationary thread controlling cam 31 is curved and the curvature is eccentric to the axis of oscillation of the looper, and this eccentric surface is so set relative to the thread guides retaining the looper thread on the forward shoulder 35 of the stationary-thread controlline' cam.

lVhen the looper is at the rear end of its stroke, the thread guides 27 and 28 are so positioned that the looper thread passing between said thread guides is below the shoulder 34. The thread guides are also some distance below the extreme end of the thread guiding tube 26. As the looper moves forward, the looper thread will be brought into contact with the shoulder 34, and this shoulder cooperating with the movable thread guides will cause all of the slack thread formed by the forward movement of the loop or to betaken up and thelooper thread drawn back through the eye of the looper. Thus it is that the slack is taken out of the looper thread, and there is no liability of the looper thread buckling as the point of the looper approaches the needle thread loop. If such buckling of the looper thread occurs, it is apt to push the needle thread loops to one side, and thus cause a skipping of stitches. The shaping of the shoulder 34 is such that when the looper point has entered the needle thread a loop or loops, provided a plurality of needles are used, and the eye of the looper is approximately opposite the first needle, the looper thread is drawn off from said shoulder so that between the threadguides 27 and 28 will be carried against the portion of thecurvedsurface 36 adjacent the shoulder 35. The pur pose of this contact of thelooper thread with the edge of the stationary member is to aid in the pulling of the looper thread from the supply of thread provided by the pull-off, and furthermore, to aid in insuring that there will be sufficient tension on the looper thread to cause it to snapin front of the shoulder on the stationary thread controlling member-V In Figures 5 and 6 of the drawings, the looper isat the rear end of its stroke, and the looper thread is about to be placed against the shoulder 34.

In Figures 4, 4c, 7 and the looper thread is against the shoulder35. This shoulder 35 on the stationary thread controlling cam operates to hold the looper thread when the looper is retracted. This is for the purpose of taking up the slack in 8 of the drawings,

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the looper thread as the looper movesba-ck and moves laterally sons to provide a thread triangle into which the needles will enter with certainty. In order to insure that the looper thread will be held on the shoulder 35 until. the points of the needles are well down into thethread triangle, the member 11 of, the needle guard during-the lateral movement of the looper comes right up close to the side face of the stationary thread controlling cam as shown in Fig. 10. When, however, the needles are well down into the looper thread loop or thread triangle, then this member 11 will have moved back away from the shoulder 35, asulficient distance so as to permit the looper thread to slide therefrom. lVhen, however, the needle guard moves laterally, and the looper thread is entirely released from any control thereby, said looper thread will be drawn taut between the thread guides 27 and 28 by reason of the fact that these thread guides will then be moving away from the thread guiding tube 26. This drawing of the thread taut at this time has little or no etl'ect upon the stitch formation, but it does position the looper thread so that it can be properly drawn against the shoulder 34 when the looper starts on its forward movement.

In Fig. 10 I have shown the position of the member on the needle guard relative to the stationary thread cam which aids in the holding of the looper thread on the upper shoulder of the stationary thread controlling cam. The looper is on its retracting movement and the needle guard is, therefore, moving in the direction of the arrow in this figure. and will soon reach a point where the thread will be drawn oil from the shoulder, due to the fact that the thread guides are moving away from this shoulder and the member on the needle guard is uncovering the shoulder.

In Fig. 11 of the drawings, I have shown the looper well toward the forward end of its stroke, and the looper thread carried against the under face 36 of the stationary thread controlling cam, so that the slack is taken out of the looper thread and the looper thread made sufiiciently taut so as to snap around in front of the shoulder The looper thread is indicated at 1 in the drawings. In Figures 12 and 13 I have shown a little more clearly the manner whereby the arm 2i clamps the looper thread. This arm 24- moves directly beneath the bar 23 and will more the thread along the slot '32 until the thread is brought against the end of the slot, and thus the thread clamped. This clamping of the thread occurs when the needles are on the lower part of their down stroke, and at this time, the looper is retracted and is about to move tori "ard into the needle thread loops. hile the looper thread is clamped by the arm 24, the arms 13 and 21 moving away from the thread guide 16 and the slot 22 after the looper thread is clamped, will draw thread from the supply, and this thread is given up when the needle clamp is open, so that the thread guides associated with the looper may draw the thread through and sup ply the same to the looper.

It will be noted from the above description that: I have provided a thread controlling mechanism for a looper thread wherein the thread passes directly from said thread controlling mechanism to the looper without engaging any thread guides whatever. It will also be noted that the thread guiding tube 26 terminates substantially at the end of the work supporting arm and that the looper and the thread controlling mechanism for the looper thread are all locateii'l beyond the end of the work supporting arm.

The machine is particularly adapted for use in connection with a plurality of needles, and a covering thread which is laid back and forth in front of the needles by a thread laying device of the usual type. This covering thread is indicated at c in the drawings. Said covering thread passes through a slot 12" in the arm 13, thence through a guide eye 16, then behind the arm 21., and thence through a thread guiding eye 16'. This covering thread is not clamped, but the arm 21 does pull the thread from the supply.

\Vhile I have shown and described the invention as applied to a machine having a plurality of needles. it will be understood that a single needle could be used with just as much advantage. The thread controlling mechanism is especially useful in a multiple needle machine wherein the looper enters all of the needle loops, as the thread controlling mechanim is closely positioned relative to the looper and will much more quickly and elliciently handle the slack thread.

lVhile I have shown my improvement as applied to a machine having a work supporting arm wherein the n'iaterial is led from the end of the arm, it will he understood that it can also be used equally as well with a flat bed machine. Then again, while I have shown the invention as applied to a machine wherein the looper moves in a plane at right angles to the line of feed. it will be understood that the looper may be otherwise disposed relative to the line of feed. In the particular type of machine illustrated, the looper supporting shaft extends beyond the end of the arm, and the entire thread controlling mechanism. associated with the looper. exclusive of the looper thread clamp and pull-otl', is beyond the end of the looper supporting arm.

It is obvious that minor changes in the details of construction and the arrangen'ient of the parts may be made without: depart ng from the spirit of the invention as set forth in the appendedclaims.

Having thus described the invention, what I claim as new and desire to secure by Letters Patent. is

1. In a sewing machine, the combination of a looper carrier. a looper mounted thereon, a thread controlling mechanism for said looper including a stationary cam member, and a movable member mounted on the looper carrier adjacent the looper and cooperating with said stationary member.

In a sewing n'iachine, the combination of a looper carrier, :1 looper mounted thereon, a thread controlling mechanism for E-Tfllll looper including a stationary cam member, and movable thread guides mounted on the looper carrier :nljaccnt the looper and cooperating with said stationary cam meinbir.

3. In a sewing machine, the combination lla- .of a looper carrier, a looper'mounted there- ;thread on the first on, athread controllingmechanism for said looper carrier adjacent the looper and cooperating with said. stat onary cam member, SfllCl;jSt3tl.Ol1&I V cam member having a shoulder against which the thrcadbetween the thread guides is carried during the oscillation of the carrier for talnngup the ment of the looper; j a

4. In a sewmg machine, the combination of a looper carrier, a looper mounted thereon, a thread controlling mechanism for said 100381 including a stationar cam member and movaole thread guides mounted on the looper c rrier adjacent the looper and cooperat her, said stationary cam member having a shoulder for engaging the thread between the thread guides for taking up the looper thread on the first part'of the backward movement of the looper.

In a sewing machine, the combination of a looper carrier, a looper mounted thereon, a thread controlling mechanism forsaid looper including a stationary cam member,

movable thread guides mounted on the looper carrier and cooperating with said stationary cam member, said stationary cam member having a shoulderffor engaging the thread between the thread guides for taking up the looper thread on the first part of the backward movement of the looper, a needle guard mounted on the looper carrier and having a projecting member adapted to move close up to the stationary thread controlling,

cam for holding the looper thread on said shoulder.

6. In a sewing machine, the combination of a looper carrier, a looper mounted thereon, a thread controlling mechanism for said looper including a stationary cam member,

movable thread guides mounted on the looper carrier adjacent the looper andcooperating with saidstationary cam member, said stationary cam member having a shoulder against which the looper thread is carried by said thread guides for taking up the thread on the first part of the forward movement of the looper, and a shoulder for engaging the looper thread for taking up the thread on the first part of the backward movement of the looper.

7. In a sewlng'machine, the combination of a looper carrier, a looper mounted thereon, a thread controlling mechanism for said looper including a stationary cam member, movable thread guides mounted on the looper carrierand cooperating with said stationary cam member, said stationary cam member having a shoulder against which the looper thread is carried by said thread guides for taking up the thread on the first part of the part of the forward move with said stationary cam memforward movement of the looper, a shoulder for engaging the looper thread for taking up the thread on the first part of the backward movement of thelooper, said stationary cam member being cut away between said shoulders to form a clearance space, andan eccentric surface so that the thread after leaving the first-named shoulder passes into "he clearance space and gives slack to the looper, and so that the looper thread is carried by the. thread guides against saideccentric-surface for. taking the slack from the. looper thread as the looper approachesthe forward end of its stroke.

S. In a. sewing machine, the combination of a. worksupporting, arm, a looper, shaft mountedin said arm and projecting beyond the end thereof, a loop'er carrier mounted on the end of said shaft, spaced thread guides mounted on said looper carrier,a stationary thread cam mounted on the end of said arm and located between said thread guides, said thread guides and'said stationary cam member cooperating to take up; the looper thread on the first part of the forward movement of the loop-er, then give slack to the looper as it moves into the needle thread loop, then 7 outer end of said work supporting arm and disposed between said thr ad guides and cooperating with said thread guides for con trolling the looper thread during the forward andbackward movement of the looper 10. In a sewing machine, the combination of a work supporting arm, a looper shaft mounted in said work supporting arm, a looper carrier mounted on said shaft, a. thread carrying looper mounted in said carrier, a thread guiding tube mounted on said work supporting arm and terminating at the end thereof, a thread controlling mechanism disposed at the end of the work'supporting arm and operatingupon the thread between the end of said tubeand the eyes of said looper for controlling the looper thread, said thread controlling mechanism including spaced thread guides mounted on the looper carrier adjacent the looper, and a stationary cam mounted on'the end of the work supporting arm and located between said thread guides.

11; In a sewing machine, the combination of a work supporting arm, a looper shaft mounted in said 4 work supporting arm, a

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looper carrier mounted on said shatt a thread carrying looper mounted in said carrierQ'a thread guiding tube mounted on said work supporting arm and terminating at the end thereof, a thread controlling mechanism disposed at the end of the work supporting arm and operating upon the thread between the end of said tube and the eyes of said looper for controlling the looper thread, said thread controlling mechanism including spaced thread guides mounted on the looper carrier. and a stationary cam mounted on the end of the work supporting arm and located between said thread guides, said stationary cam having spaced thread engaging shoulders and cut away between said shoulders so as to form a clearance space for the looper thread atter leaving one shoulder before it is brought into engagement with the other.

12. In a sewing machine, the combination of a work supporting arm, a looper shaft mounted in said work supporting arm. a looper carrier mounted on said shaft, a thread carrying looper mounted in said carrier, a thread guiding tube mounted on said work supporting arm and terminating at the end thereof, a thread controlling mechanism disposed at the end of the, work supporting arm and operating upon the thread between the end of said tube and the eyes of said looper for controlling the looper thread. said thread controlling mechanism including spaced thread guides mounted on the looper carrier, a stationary cam mounted on the end of the work supporting arm and located between said thread guides, said sta tionary cam having spaced thread engaging shoulders and cut away between said shoulders so as to form a clearance space for the looper thread after leaving one shoulder he fore it is brought into engagement with the other, and a member mounted on said looper carrier and cooperating with said stationary cam for retaining: the looper thread on one of said shoulders.

In testimony whereof, I afiix my signature.

JAMES R. MOFFATT. 

